Blade structure for a radial airflow fan

ABSTRACT

A fan includes a hub rotatable about an axis and having an open end and a closed end, and a plurality of blades extending from the hub. Each of the blades has a leading side surface, a trailing side surface, an inner lateral edge corresponding to the open end of the hub, an outer lateral edge corresponding to the closed end of the hub, and a radial outer edge having opposite inner and outer ends connected respectively to the inner and outer lateral edges, and at least one end portion extending from one of the inner and outer ends toward both the axis and one of the inner and outer lateral edges.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a fan, and more particularly to a blade structure for a radial airflow fan.

2. Description of the Related Art

Referring to FIG. 1, a conventional heat dissipation fan includes a thermally conductive housing 1 and a fan 2 disposed rotatably within the housing 1. The housing 1 has a wall 11, an air inlet 12 formed through a top wall portion of the wall 11, and an air outlet 13 formed through an annular wall portion of the wall 11. The fan 2 includes a hub 21 and a plurality of blades 22 extending from the hub 21. Each of blades 22 has an inner lateral edge 221 distal from the air inlet 12, an outer lateral edge 221′ proximate to the air inlet 12 and opposite to the inner lateral edge 221, and a radial outer edge 222 interconnecting corresponding ends of the inner and outer lateral edges 221, 221′.

When the fan 2 rotates, air is sucked into the housing 1 through the air inlet 12, and is removed from the housing 1 through the air outlet 13. Thus, heat is dissipated from the housing 1.

A drawback of the aforesaid conventional fan is that, because the radial outer edge 222 of each of the blades 22 is parallel to the rotating axis of the hub 21, a substantial amount of radial airflow produced during rotation of the blades 22 comes into contact with an inner surface of the wall 11. This results in the significant generation of noise.

SUMMARY OF THE INVENTION

The object of this invention is to provide a fan for producing a radial airflow that generates low noise when the fan rotates within a thermally conductive housing to serve as a heat dissipation fan.

According to this invention, a fan includes a hub rotatable about an axis and having an open end and a closed end, and a plurality of blades extending from the hub. Each of the blades has a leading side surface, a trailing side surface, an inner lateral edge corresponding to the open end of the hub, an outer lateral edge corresponding to the closed end of the hub, and a radial outer edge having opposite inner and outer ends connected respectively to the inner and outer lateral edges, and at least one end portion extending from one of the inner and outer ends toward both the axis and one of the inner and outer lateral edges. As such, when the fan rotates within a thermally conductive housing to serve as a heat dissipation fan, it can produce a radial airflow that generates a minimal amount of noise.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of this invention will become apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of a conventional fan;

FIG. 2 is a perspective view of the first preferred embodiment of a radial airflow fan according to this invention;

FIG. 3 is a sectional view of the first preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 4 is a perspective view of the second preferred embodiment of a radial airflow fan according to this invention;

FIG. 5 is a sectional view of the second preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 6 is a perspective view of the third preferred embodiment of a radial airflow fan according to this invention;

FIG. 7 is a sectional view of the third preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 8 is a perspective view of the fourth preferred embodiment of a radial airflow fan according to this invention;

FIG. 9 is a sectional view of the fourth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 10 is a perspective view of the fifth preferred embodiment of a radial airflow fan according to this invention;

FIG. 11 is a sectional view of the fifth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 12 is a perspective view of the sixth preferred embodiment of a radial airflow fan according to this invention;

FIG. 13 is a sectional view of the sixth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 14 is a perspective view of the seventh preferred embodiment of a radial airflow fan according to this invention;

FIG. 15 is a sectional view of the seventh preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 16 is a perspective view of the eighth preferred embodiment of a radial airflow fan according to this invention;

FIG. 17 is a sectional view of the eighth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 18 is a perspective view of the ninth preferred embodiment of a radial airflow fan according to this invention;

FIG. 19 is a sectional view of the ninth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated;

FIG. 20 is a perspective view of the tenth preferred embodiment of a radial airflow fan according to this invention; and

FIG. 21 is a sectional view of the tenth preferred embodiment, illustrating how a radial airflow produced during rotation of the fan is concentrated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail in connection with the preferred embodiments, it should be noted that similar elements and structures are designated by like reference numerals throughout the entire disclosure.

Referring to FIGS. 2 and 3, the first preferred embodiment of a radial airflow fan according to this invention is disposed rotatably within a thermally conductive housing 3 that has a wall 31, an air inlet 32 formed through a top wall portion of the wall 31, and an air outlet 33 formed through an annular wall portion of the wall 31. The fan includes a hub 4 and a fan unit consisting of a plurality of equidistant blades 5.

The hub 4 is rotatable about an axis (X), and has a peripheral wall 41, an open end 42, and a closed end 43.

The blades 5 extend from the peripheral wall 41 of the hub 4. Each of the blades 5 has a leading side surface 50, a trailing side surface 50′ opposite to the leading side surface 50, an outer lateral edge 51 corresponding to the closed end 43 of the hub 4, an inner lateral edge 52 corresponding to the open end 42 of the hub 4 and opposite to the outer lateral edge 52, and a radial outer edge 53 having opposite inner and outer ends 530, 530′ connected respectively to the inner and outer lateral edges 52, 51.

In this embodiment, for each of the blades 5, the radial outer edge 53 has an inclined straight outer edge portion 531 extending from the outer end 530′ toward both the axis (X) and the inner lateral edge 52, and an inclined straight inner edge portion 532 extending from the inner end 530 toward both the axis (X) and the outer lateral edge 51. An imaginary extension line (not shown) of each of the inner and outer edge portions 532, 531 forms an acute angle with respect to the axis (X)

When the blades 5 rotate, air is sucked into the housing 3 through the air inlet 32, and is removed from the housing 3 through the air outlet 33. Thus, heat is dissipated from the housing 3.

Advantageously, air is directed by the inclined straight inner and outer edge portions 532, 531 to flow toward a middle portion of the annular wall portion of the wall 31 of the housing 3, as shown in FIG. 3. As such, noise created from friction between air and an inner surface of the wall 31 can be reduced.

FIGS. 4 and 5 show the second preferred embodiment of a radial airflow fan according to this invention. In contrast to the first preferred embodiment, the radial outer edge 53 of each of the blades 5 is concaved and curved, and is disposed nearest the axis (X) at a middle portion thereof. The imaginary tangent line (not shown) of each point of the radial outer edge 53 of each of the blades 5 forms an acute angle with respect to the axis (X).

FIGS. 6 and 7 show the third preferred embodiment of a radial airflow fan according to this invention. In contrast to the first preferred embodiment, the blade unit includes a plurality of adjacent blade pairs 5′, each of which consists of a first blade (5A) and a second blade (5B). The blade unit further includes a third blade (5C) similar in construction to the first blades (5A).

For each of the first blades (5A), the radial outer edge 53 has an inclined straight outer edge portion 531 extending from the outer end 530′ toward both the axis (X) and the inner lateral edge 52 and having an imaginary extension line (not shown) forming an acute angle with respect to the axis (X), and an axial straight inner edge portion 532 extending from the inner end 530 toward the outer lateral edge 51 along a direction parallel to the axis (X) and having an end connected to an end of the inclined straight outer edge portion 531.

For each of the second blades (5B), the radial outer edge 53 has an inclined inner edge portion 531 extending from the inner end 530 toward the axis (X) and the outer lateral edge 51 and having an imaginary extension line (not shown) forming an acute angle with respect to the axis (X), and an axial outer edge portion 532 extending from the outer end 530′ toward the inner lateral edge 52 along a direction parallel to the axis (X).

FIGS. 8 and 9 show the fourth preferred embodiment of a radial airflow fan according to this invention, which is a modification of the third preferred embodiment. In this embodiment, each of the blades 5 is similar in construction to the second blades (5B) (see FIG. 6) of the third preferred embodiment.

FIGS. 10 and 11 show the fifth preferred embodiment of a radial airflow fan according to this invention, which is a modification of the third preferred embodiment. In this embodiment, each of the blades 5 is similar in construction to the first blades (5A) (see FIG. 6) of the third preferred embodiment.

FIGS. 12 and 13 show the sixth preferred embodiment of a radial airflow fan according to this invention. In contrast to the first preferred embodiment, for each of the blades 5, the radial outer edge 53 is straight, and extends from the inner end 530 toward both the axis (X) and the outer lateral edge 51. An imaginary extension line (not shown) of the radial outer edge 53 of each of the blades 5 forms an acute angle with respect to the axis (X).

FIGS. 14 and 15 show the seventh preferred embodiment of a radial airflow fan according to this invention, which is a modification of the sixth preferred embodiment. In contrast to the sixth preferred embodiment, for each of the blades 5, the radial outer edge 53 extends from the outer end 530′ toward both the axis (X) and the inner lateral edge 52.

FIGS. 16 and 17 show the eighth preferred embodiment of a radial airflow fan according to this invention. In contrast to the first preferred embodiment, for each of the blades 5, the radial outer edge 53 is curved, extends from the inner end 530 toward both the axis (X) and the outer lateral edge 51, and is disposed nearest the axis (X) at the outer end 530′. An imaginary tangent line (not shown) of each point of the radial outer edge 53 of each of the blades 5 forms an acute angle with respect to the axis (X).

FIGS. 18 and 19 show the ninth preferred embodiment of a radial airflow fan according to this invention, which is a modification of the eighth preferred embodiment. In contrast to the eighth preferred embodiment, for each of the blades 5, the radial outer edge 53 extends from the outer end 530′ toward both the axis (X) and the inner lateral edge 52, and is disposed nearest the axis (X) at the inner end 530.

FIGS. 20 and 21 show the tenth preferred embodiment of a radial airflow fan according to this invention. In contrast to the first preferred embodiment, the blade unit includes a plurality of adjacent blade pairs 5″, each of which consists of a first blade (5D) and a second blade (5E). The blade unit further includes a third blade (5F) similar in construction to the first blades (5D). In this embodiment, each of the first blades (5D) is similar in construction to the blades 5 of the ninth preferred embodiment, and each of the second blades (5E) is similar in construction to the blades 5 of the eighth preferred embodiment.

With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims. 

1. A fan comprising: a hub rotatable about an axis and having a peripheral wall, an open end and a closed end; and a plurality of blades extending from said peripheral wall of said hub, each of said blades having a leading side surface, a trailing side surface opposite to said leading side surface, an inner lateral edge corresponding to said open end of said hub, an outer lateral edge corresponding to said closed end of said hub and opposite to said inner lateral edge, and a radial outer edge having opposite inner and outer ends connected respectively to said inner and outer lateral edges, and at least one end portion extending from one of said inner and outer ends toward both said axis and one of said inner and outer lateral edges.
 2. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades has an inclined straight inner edge portion extending from said inner end of said radial outer edge of a corresponding one of said blades toward both said axis and said outer lateral edge of the corresponding one of said blades, and an inclined straight outer edge portion extending from said outer end of said radial outer edge of the corresponding one of said blades toward both said axis and said inner lateral edge of the corresponding one of said blades, an imaginary extension line of each of said straight inner and outer edge portions forming an acute angle with respect to said axis.
 3. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades is concaved and curved, and is disposed nearest said axis at a middle portion thereof, an imaginary tangent line of each point of said radial outer edge of each of said blades forming an acute angle with respect to said axis.
 4. The fan as claimed in claim 1, wherein said blades include a plurality of adjacent pairs of blades, said radial outer edge of one of each adjacent pair of said blades having an axial straight inner edge portion extending from said inner end of said radial outer edge of a corresponding one of said blades toward said outer lateral edge along a direction parallel to said axis, and an inclined straight outer edge portion extending from said outer end of said radial outer edge of the corresponding one of said blades toward both said axis and said inner lateral edge of the corresponding one of said blades and having an imaginary extension line forming an acute angle with respect to said axis, and an end connected to an end of said inner edge portion, said radial outer edge of the other one of each adjacent pair of said blades having an axial straight outer edge portion extending from said outer end of said radial outer edge of a corresponding one of said blades toward said inner lateral edge along a direction parallel to said axis, and an inclined straight inner edge portion extending from said inner end of said radial outer edge of the corresponding one of said blades toward both said axis and said outer lateral edge of the corresponding one of said blades and having an imaginary extension line forming an acute angle with respect to said axis, and an end connected to an end of said outer edge portion.
 5. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades has an axial straight outer edge portion extending from said outer end of said radial outer edge of a corresponding one of said blades toward said inner lateral edge along a direction parallel to said axis, and an inclined straight inner edge portion extending from said inner end of said radial outer edge of the corresponding one of said blades toward both said axis and said outer lateral edge of the corresponding one of said blades and having an imaginary extension line forming an acute angle with respect to said axis, and an end connected to an end of said outer edge portion.
 6. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades has an axial straight inner edge portion extending from said inner end of said radial outer edge of a corresponding one of said blades toward said outer lateral edge along a direction parallel to said axis, and an inclined straight outer edge portion extending from said outer end of said radial outer edge of the corresponding one of said blades toward both said axis and said inner lateral edge of the corresponding one of said blades and having an imaginary extension line forming an acute angle with respect to said axis, and an end connected to an end of said inner edge portion.
 7. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades is straight, and extends from said inner end of said radial outer edge of a corresponding one of said blades toward both said axis and said outer lateral edge of said radial outer edge of the corresponding one of said blades, an imaginary extension line of said radial outer edge of each of said blades forming an acute angle with respect to said axis.
 8. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades is straight, and extends from said outer end of said radial outer edge of a corresponding one of said blades toward both said axis and said inner lateral edge of said radial inner edge of the corresponding one of said blades, an imaginary extension line of said radial outer edge of each of said blades forming an acute angle with respect to said axis.
 9. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades is curved, extends from said inner end of said radial outer edge of a corresponding one of said blades toward both said axis and said outer lateral edge of the corresponding one of said blades, and is disposed nearest said axis at said outer end of said radial outer edge of the corresponding one of said blades, an imaginary tangent line of each point of said radial outer edge of each of said blades forming an acute angle with respect to said axis.
 10. The fan as claimed in claim 1, wherein said radial outer edge of each of said blades is curved, extends from said outer end of said radial outer edge of a corresponding one of said blades toward both said axis and said inner lateral edge of the corresponding one of said blades, and is disposed nearest said axis at said inner end of said radial outer edge of the corresponding one of said blades, an imaginary extension line of each point of said radial outer edge of each of said blades forming an acute angle with respect to said axis.
 11. The fan as claimed in claim 1, wherein said blades include a plurality of adjacent pairs of blades, said radial outer edge of one of each adjacent pair of said blades being curved, an imaginary tangent line of each point of said radial outer edge of each of said blades forming an acute tangential angle with respect to said axis, said radial outer edge of each adjacent pair of said blades extending from said inner end of said radial outer edge of a corresponding one of said blades toward both said axis and said outer lateral edge of the corresponding one of said blades and being disposed nearest said axis at said outer end of said radial outer edge of the corresponding one of said blades, said radial outer edge of the other one of each adjacent pair of said blades extending from said outer end of said radial outer edge of a corresponding one of said blades toward both said axis and said inner lateral edge of the corresponding one of said blades and being disposed nearest said axis at said inner end of said radial outer edge of the corresponding one of said blades. 